There has been considerable recent interest in halogen-substituted hydrocarbons containing flourine and hydrogen, particularly halogen-substituted ethanes. Many of these materials can be used as refrigerants, blowing agents, or as chemical starting materials for the production of refrigerants or blowing agents. Some such as CF.sub.3 CH.sub.2 F (i.e., HFC-134a) are being considered to replace fully halogenated hydrocarbons containing chlorine which are less environmentally desirable due to their interaction with the earth's ozone layer.
Various processes have been disclosed for the production of halogen-substituted ethanes containing fluorine and hydrogen. For example, British Patent Specification 1,000,485 discloses a process for the preparation of organic fluorinated compounds (e.g., CF.sub.3 CH.sub.2 Cl or CF.sub.3 CHCl.sub.2) by fluorination of haloolefins (e.g., CCl.sub.2 .dbd.CHCl or CCl.sub.2 .dbd.CCl.sub.2) in a gaseous phase at an elevated temperature using an activated alumina (e.g., alumina activated by impregnation with a solution of one or more halides of polyvalent metals such as chromium, cobalt, nickel and manganese) which is partially fluorinated. U.S. Pat. No. 4,766,260 discloses a gas-phase process for the manufacture of CF.sub.3 CHCl.sub.2 and CF.sub.3 CHClF by fluorination of a suitable tetrahaloethylene (e.g., CCl.sub.2 .dbd.CCl.sub.2) using a selected metal on a high fluorine content alumina support. U.S. Pat. No. 4,861,744 discloses the formation of CF.sub.3 CH.sub.2 F (and CF.sub.3 CH.sub.2 Cl) by the vapor phase fluorination of a suitable trihaloethylene (e.g., CCl.sub.2 .dbd.CHCl) using a catalyst prepared by codepositing a hexavalent chromium oxide and a transition metal compound (e.g., titanium trichloride) on alumina followed by fluorinating the resulting combination. Japanese Patent Application Publication 2-172933 discloses a method for manufacturing CF.sub.3 CH.sub.2 F by fluorinating CF.sub.3 CH.sub.2 Cl in the presence of a fluorinating catalyst which contains a halide or oxide which contains chromium and at least one element selected from among aluminum, magnesium, calcium, barium, strontium, iron, nickel, cobalt and manganese (e.g., catalyst produced by adding a commercial alumina to a solution of chromium chloride, drying the mixture, and activating the residue using HF).
Aluminum fluoride may be obtained by the fluorination of alumina. Several phases of aluminum fluoride have been reported, each having a characteristic powder X-ray diffraction pattern.
.alpha.-AlF.sub.3 (i.e., alpha-aluminum fluoride) as reported by E. Staritzky and L. B. Asprey, Anal. Chem., 29, 984 (1957) has a powder x-ray diffraction pattern characterized by various "d" spacings between 3.520 Angstroms and 1.560 Angstroms with the strongest intensity observed at a "d" spacing of 3.520 Angstroms. .beta.-AlF.sub.3 (i.e., beta-aluminum fluoride) as reported by U.S. Pat. No. 3,178,483 has a powder X-ray diffraction pattern characterized by various "d" spacings between 6.000 Angstroms and 1.558 Angstroms with very strong intensities observed at "d" spacings of 6.000 Angstroms and 3.563 Angstroms and strong intensities observed at "d" spacings of 3.465 Angstroms and 3.001 Angstroms. .gamma.-AlF.sub.3 (i.e., gamma-aluminum fluoride) as reported by U.S. Pat. No. 3,178,484 has a powder X-ray diffraction pattern characterized by various "d" spacings between 3.537 Angstroms and 1.623 Angstroms with very strong intensity observed at a "d" spacing of 3.537 Angstroms and a strong intensity observed at a "d" spacing of 1.768 Angstroms.
Processes using particular phases of AlF.sub.3 have been disclosed. For example, European Patent Publication 0282005 discloses a process for preparing CF.sub.3 CHCl.sub.2 (and CF.sub.3 CHClF) by reacting CCl.sub.2 .dbd.CCl.sub.2 with HF in the gas phase in the presence of catalysts comprising Cr.sub.2 O.sub.3 carried on AlF.sub.3 in the gamma and/or beta form. Japanese Patent Application Publication 53-144509 discloses a process for the manufacture of 3,3,3-trifluoropropene using a catalyst bed comprising .alpha.-aluminum fluoride and a second catalyst comprising other gas-phase fluorinating catalysts (e.g., .beta.-aluminum fluoride and/or .gamma.-aluminum fluoride).